The U.S. Department of Energy has turned its focus to the water-energy nexus as the sectors start to see the impact of climate change.

In an effort to bring more integrated research across its programs, the DOE’s Water-Energy Tech Team issued a new report this month, The Water-Energy Nexus: Challenges and Opportunities.

The findings are hardly novel. There are huge inefficiencies in how water is used and great regional variability. The Sankey diagram below shows the magnitude of water waste in the energy sector, particularly in thermoelectric power generation.

Click image to enlarge.

Thermoelectric generation is responsible for more than 40 percent of freshwater withdrawals and 4 percent of freshwater consumption in the U.S. More than 95 percent of marine withdrawals go to thermoelectric cooling, which includes nuclear, coal, gas, geothermal and CSP.

“Increased deployment of some energy technologies in the future, such as carbon capture and sequestration, could lead to increases in the energy system‘s water intensity,” the study authors state, “whereas deployment of other technologies, such as wind and solar photovoltaics could lower it."

The opportunities will come not only in technology innovation in cooling technology, such as in air flow designs, water recovery, hybrid wet/dry systems and alternative cooling, but also in simply retiring older, once-through cooling systems. Once-through cooling systems delivered nearly 23 percent of electricity in the U.S. in 2011, but withdrew about two-thirds of the overall water used by power plants.

More than half of the coal-fired power plants in the U.S. use once-through cooling, according to the U.S. Energy Information Administration. But that may change -- and fast. Earlier this year, the EIA increased its short-term coal retirement prediction by 50 percent. It now sees 60 gigawatts of coal coming offline by 2016.

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